<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>组合选择器</title>
    <style>
        <!--后代选择器-->
        .top li{
            color: #a141ff;
        }
        .center>li{
            color: green;
        }
        /*分组选择器*/
        .center,p{
            color: darkorange;
        }
    </style>
</head>

<body>

<div class="top">
    <ol>
        <li>aaa</li>
        <li>bbb</li>
    </ol>
</div>

<div class="center">
    <li>xxx</li>
    <ol>
        <li>ccc</li>
        <li>ddd</li>
    </ol>
</div>
<p>ddcnjd</p>
</body>
</html>